Fluxbox is a simple window manager, meaning that by default there is not much decoration.
- rounded corners
- borderless windows - useful for terminals
- transparency - allows transparency on borders and the menu
- true transparency - using xcompmgr
- add icons to your menu
To display some nice details about your computer, memory usage etc. use Conky or torsmo that show the info over the background image (the root window). You can also use GKrellm that will go nicely to the slit when launching like gkrellm -w.
Other nice eye candy things are GDesklets and ADesklets that allow you to have almost anything on your dekstop. Anything from launcbars to weather forecasts and tv programs lists. You can also get a floating duck with bubblemon.